East Anglia with 33Mm on Average Across the Area, Although with Significant Local Variation

Monthly water situation report East of England

Summary – August 2021 August had below normal rainfall in East Anglia with 33mm on average across the area, although with significant local variation. Soil Moisture Deficit (SMD) continued to increase but remains normal for the time of year. As expected river flows reduced throughout August at almost all indicator sites, although rivers in the North Norfolk catchments retained flows above normal or higher. Groundwater levels also continued to reduce, but all indicator sites in East Anglia remain normal or higher for the time of year and reflecting this, environmental support remained similar to July. All reservoir levels in the area remain above the normal operating curve.

Rainfall East Anglia had an average of 33mm of rainfall in August which is classified as below normal for the time of year with 64% of the Long Term Average (LTA). The majority of the rainfall fell at two points within the month around the 5th-9th and 21st-22nd. The rainfall distribution was quite varied with the North Norfolk catchment receiving 46mm (77% LTA; normal) and North and South Essex catchments receiving 40 and 38mm respectively (83% and 82% LTA; normal), whilst the Little Ouse and Lark catchment had only 28mm and was classified as notably low (52% LTA). Totals over the previous 12 months across the area remain above normal with 122% of LTA recorded.

Soil Moisture Deficit/Recharge SMD continued to increase throughout the month of August, albeit with a slight decrease in the second week in response to the rainfall. By the end of the month the SMD value reached 106mm, which is still classified as normal for the time of year. A similar spatial pattern to the previous month remains with slightly lower values to the south west and higher values to the north and around the coast.

River Flows River flows throughout East Anglia continued to decrease during August at all indicator sites, as expected for the time of year, with the exception of the river Bure in North Norfolk. Across the area 86% of flows at indicator sites remain normal or higher, with 29% above normal and the river Burn in North Norfolk sustaining notably high flows for the time of year. The rivers Cam, Waveney and Tove all recorded below normal flows in August.

Groundwater Levels Groundwater levels at all reported indicator sites continued to reduce in August, again as expected for the time of year. However, all sites in East Anglia remain normal or higher for the time of year with 50% of recorded sites having above normal levels. 17% of sites still retain notably high levels for the time of year – Bircham Newton in the North West Norfolk Chalk, Biggleswade in the Ivel Sandstone and Fringford in the Great Oolite.

Reservoir Storage/Water Resource Zone Stocks Reservoir levels have remained steady at two of the five reservoirs in the area (Grafham and Hanningfield) and have slightly reduced at three of the five reservoirs (Ardleigh, Abberton and Alton). All reservoirs end the month above their normal operating curve and, with the exception of Abberton which is classified as normal, all have levels classified as above normal or higher for the time of year.

Environmental Impact Groundwater support scheme operations have largely remained the same in August, with a slight increase in pumping hours for pumps already in operation. The Lodes-Granta groundwater support scheme had 4 of the 6 pumps operating while the Rhee groundwater support scheme had 2 of the 8 pumps operating. The Hiz and Thet-Little Ouse schemes both remained with no pumping.

All data are provisional and may be subject to revision. The views expressed in this document are not necessarily those of the Environment Agency. Its officers, servants or agents accept no liability for any loss or damage arising from the interpretation or use of the information, or reliance upon views contained herein. © Environment Agency 2021

Forward Look

Probabilistic ensemble projections for river flows at key sites September 2021: There is an increased probability of flows above normal or higher in the Ivel, and of notably high flows in the Bedford Ouse and Ouse in September. There is a significantly increased probability of below normal flows in the Ely Ouse. All sites (except the Gipping) have a reduced probability of notably or exceptionally low flows in September. December 2021: There is a reduced probability of exceptionally low flows in December, and an increased probability of above normal flows in the Upper Ouse catchment.

Probabilistic ensemble projections for groundwater levels in key aquifers September 2021: There is a significantly increased probability that groundwater levels will be normal or above normal at all key sites in September. March 2022: There is a reduced probability of exceptionally low groundwater levels at Bircham Newton and Washpit Farm, Rougham in the North West Norfolk Chalk in March 2022. There is a slightly increased probability of groundwater levels below normal or lower at Newmarket (Snail Chalk) and Kenninghall (Little Ouse Chalk).

Author: ANG-Hydrology Contact details: 03708506506

Rainfall August 2021

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Above average rainfall Below average rainfall 1-Month Period for East Anglia 1-Month Period for Upper Bedford Ouse

250% 300%

250% 200%

200% 150%

150%

100% 100%

50% 50%

0% 0%

Mar-21 Mar-21 Sep-20 Oct-20 Nov-20 Dec-20 Jan-21 Feb-21 Apr-21 May-21 Jun-21 Jul-21 Aug-21 Sep-20 Oct-20 Nov-20 Dec-20 Jan-21 Feb-21 Apr-21 May-21 Jun-21 Jul-21 Aug-21

1-Month Period for Lower Bedford Ouse 1-Month Period for Central Area Fenland

250% 250%

200% 200%

150% 150%

100% 100%

50% 50%

0% 0%

Mar-21 Mar-21 Sep-20 Oct-20 Nov-20 Dec-20 Jan-21 Feb-21 Apr-21 May-21 Jun-21 Jul-21 Aug-21 Sep-20 Oct-20 Nov-20 Dec-20 Jan-21 Feb-21 Apr-21 May-21 Jun-21 Jul-21 Aug-21

1-Month Period for Cam 1-Month Period for NW Norfolk and Wissey

250% 250%

200% 200%

150% 150%

100% 100%

50% 50%

0% 0%

Mar-21 Mar-21 Sep-20 Oct-20 Nov-20 Dec-20 Jan-21 Feb-21 Apr-21 May-21 Jun-21 Jul-21 Aug-21 Sep-20 Oct-20 Nov-20 Dec-20 Jan-21 Feb-21 Apr-21 May-21 Jun-21 Jul-21 Aug-21

1-Month Period for Little Ouse and Lark 1-Month Period for North Norfolk

250% 250%

200% 200%

150% 150%

100% 100%

50% 50%

0% 0%

Mar-21 Mar-21 Sep-20 Oct-20 Nov-20 Dec-20 Jan-21 Feb-21 Apr-21 May-21 Jun-21 Jul-21 Aug-21 Sep-20 Oct-20 Nov-20 Dec-20 Jan-21 Feb-21 Apr-21 May-21 Jun-21 Jul-21 Aug-21

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Above average rainfall Below average rainfall 1-Month Period for Broadland Rivers 1-Month Period for East Suffolk

250% 250%

200% 200%

150% 150%

100% 100%

50% 50%

0% 0%

Mar-21 Mar-21 Sep-20 Oct-20 Nov-20 Dec-20 Jan-21 Feb-21 Apr-21 May-21 Jun-21 Jul-21 Aug-21 Sep-20 Oct-20 Nov-20 Dec-20 Jan-21 Feb-21 Apr-21 May-21 Jun-21 Jul-21 Aug-21

1-Month Period for North Essex 1-Month Period for South Essex

300% 350%

300% 250%

250% 200%

200%

150%

100% 100%

50% 50%

0% 0%

Mar-21 Mar-21 Sep-20 Oct-20 Nov-20 Dec-20 Jan-21 Feb-21 Apr-21 May-21 Jun-21 Jul-21 Aug-21 Sep-20 Oct-20 Nov-20 Dec-20 Jan-21 Feb-21 Apr-21 May-21 Jun-21 Jul-21 Aug-21

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Soil Moisture Deficit

Data based on MORECS dataset (Met Office © Crown Copyright) ─── 2020-21 ─ ─ ─ 2019-20 Exceptionally high Notably high Above normal Normal Below normal Notably low Exceptionally low ─── Latest data

East Anglia Ranking derived from data for the period Jan-1961 to Dec-2017 0

80 SMD SMD (mm) 100

120

140 Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct

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River Flow August 2021

Exceptionally high Notably high Above normal Normal - - - - Max Below normal Notably low Exceptionally low ─── Latest data - - - - Min Cappenham, TOVE Willen, OUZEL Ranking derived from data for the period Feb-1962 to Dec-2017 Ranking derived from data for the period Jan-1962 to Dec-2017

6.0 9.0 8.0 5.0 7.0 4.0 6.0 5.0 3.0 4.0

2.0 3.0

Flow (cumecs)Flow (cumecs)Flow 2.0 1.0 1.0 0.0 0.0 Nov-20 Jan-21 Mar-21 May-21 Jul-21 Sep-21 Nov-20 Jan-21 Mar-21 May-21 Jul-21 Sep-21

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Exceptionally high Notably high Above normal Normal - - - - Max Below normal Notably low Exceptionally low ─── Latest data - - - - Min Burnt Mill, RHEE Roxton, GREAT OUSE Ranking derived from data for the period Oct-1962 to Dec-2017 Ranking derived from data for the period Oct-1972 to Dec-2017

7 50 6

5 40

4 30 3

20 Flow (cumecs)Flow Flow (cumecs)Flow 2 10 1

0 0 Nov-20 Jan-21 Mar-21 May-21 Jul-21 Sep-21 Nov-20 Jan-21 Mar-21 May-21 Jul-21 Sep-21

Blunham, IVEL Offord (Gross Flows), GREAT OUSE Ranking derived from data for the period Aug-1959 to Dec-2017 Ranking derived from data for the period Jan-1972 to Dec-2017

12 70 10 60

8 50

6 40 30

4 Flow (cumecs)Flow Flow (cumecs)Flow 20 2 10

0 0 Nov-20 Jan-21 Mar-21 May-21 Jul-21 Sep-21 Nov-20 Jan-21 Mar-21 May-21 Jul-21 Sep-21

Dernford, CAM Temple, LARK Ranking derived from data for the period Feb-1949 to Dec-2017 Ranking derived from data for the period Nov-1960 to Dec-2017

5.0 5.0 4.5 4.5 4.0 4.0 3.5 3.5 3.0 3.0 2.5 2.5

2.0 2.0 Flow (cumecs)Flow Flow (cumecs)Flow 1.5 1.5 1.0 1.0 0.5 0.5 0.0 0.0 Nov-20 Jan-21 Mar-21 May-21 Jul-21 Sep-21 Nov-20 Jan-21 Mar-21 May-21 Jul-21 Sep-21

Abbey Heath, LITTLE OUSE Northwold Total, WISSEY Ranking derived from data for the period Jun-1968 to Dec-2017 Ranking derived from data for the period Jul-1983 to Dec-2012

10.0 16 9.0 14 8.0 12 7.0 10 6.0 8 5.0 4.0

6 Flow (cumecs)Flow Flow (cumecs)Flow 3.0 4 2.0 2 1.0 0 0.0 Nov-20 Jan-21 Mar-21 May-21 Jul-21 Sep-21 Nov-20 Jan-21 Mar-21 May-21 Jul-21 Sep-21

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Exceptionally high Notably high Above normal Normal - - - - Max Below normal Notably low Exceptionally low ─── Latest data - - - - Min Denver, ELY OUSE Marham, NAR Ranking derived from data for the period Nov-1971 to Dec-2017 Ranking derived from data for the period Apr-1982 to Dec-2017

4.0

50 3.5

3.0 40 2.5

30 2.0

20 1.5 Flow (cumecs)Flow Flow (cumecs)Flow 1.0 10 0.5

0 0.0 Nov-20 Jan-21 Mar-21 May-21 Jul-21 Sep-21 Nov-20 Jan-21 Mar-21 May-21 Jul-21 Sep-21

Heacham, HEACHAM Colney, YARE Ranking derived from data for the period Nov-1965 to Dec-2017 Ranking derived from data for the period Jan-1970 to Dec-2017

1.0 9.0 0.9 8.0 0.8 7.0 0.7 6.0 0.6 5.0 0.5 4.0 0.4

3.0 Flow (cumecs)Flow Flow (cumecs)Flow 0.3 0.2 2.0 0.1 1.0 0.0 0.0 Nov-20 Jan-21 Mar-21 May-21 Jul-21 Sep-21 Nov-20 Jan-21 Mar-21 May-21 Jul-21 Sep-21

Ingworth, BURE Burnham Overy, BURN Ranking derived from data for the period Jan-1970 to Dec-2017 Ranking derived from data for the period Jan-1970 to Dec-2017

3.0 2.0 1.8 2.5 1.6 1.4 2.0 1.2 1.5 1.0 0.8

1.0 Flow (cumecs)Flow Flow (cumecs)Flow 0.6 0.4 0.5 0.2 0.0 0.0 Nov-20 Jan-21 Mar-21 May-21 Jul-21 Sep-21 Nov-20 Jan-21 Mar-21 May-21 Jul-21 Sep-21

Swanton Morley Total, WENSUM Needham Weir Total, WAVENEY (LOWER) Ranking derived from data for the period Jan-1970 to Dec-2017 Ranking derived from data for the period Jan-1970 to Dec-2017

14 10.0 12

10 8.0

8 6.0 6

4.0 Flow (cumecs)Flow Flow (cumecs)Flow 4 2.0 2

0 0.0 Nov-20 Jan-21 Mar-21 May-21 Jul-21 Sep-21 Nov-20 Jan-21 Mar-21 May-21 Jul-21 Sep-21

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Exceptionally high Notably high Above normal Normal - - - - Max Below normal Notably low Exceptionally low ─── Latest data - - - - Min Bramford, GIPPING Lexden, COLNE Ranking derived from data for the period Jan-1970 to Dec-2017 Ranking derived from data for the period Jan-1970 to Dec-2017

10.0 7.0 9.0 6.0 8.0 7.0 5.0

6.0 4.0 5.0

4.0 3.0 Flow (cumecs)Flow Flow (cumecs)Flow 3.0 2.0 2.0 1.0 1.0 0.0 0.0 Nov-20 Jan-21 Mar-21 May-21 Jul-21 Sep-21 Nov-20 Jan-21 Mar-21 May-21 Jul-21 Sep-21

Springfield, CHELMER Ranking derived from data for the period Jan-1970 to Dec-2017

6.0

5.0

4.0

3.0

2.0 Flow (cumecs)Flow

1.0

0.0 Nov-20 Jan-21 Mar-21 May-21 Jul-21 Sep-21

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Groundwater Levels August 2021

Exceptionally high Notably high Above normal Normal - - - - Max Below normal Notably low Exceptionally low ─── Latest data - - - - Min Fringford - GREAT OOLITE Bath Spring, Charlton - IVEL CHALK Ranking derived from data for the period Sep-1980 to Dec-2017 Ranking derived from data for the period Mar-1993 to Dec-2017

99 72

98 71

97 70

96 69

95 68

Level (mAOD) Level Level (mAOD) Level

94 67

93 66 Nov-18 Mar-19 Jul-19 Nov-19 Mar-20 Jul-20 Nov-20 Mar-21 Jul-21 Nov-18 Mar-19 Jul-19 Nov-19 Mar-20 Jul-20 Nov-20 Mar-21 Jul-21

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Exceptionally high Notably high Above normal Normal - - - - Max Below normal Notably low Exceptionally low ─── Latest data - - - - Min Biggleswade - IVEL SANDSTONE Therfield Rectory - N HERTS CHALK Ranking derived from data for the period Mar-1968 to Dec-2017 Ranking derived from data for the period Jan-1883 to Dec-2017

28.0 100 27.7 95 27.4

27.1 90 26.8 26.5 85 26.2

80 Level (mAOD) Level

Level (mAOD) Level 25.9 25.6 75 25.3 70 25.0 Nov-18 Mar-19 Jul-19 Nov-19 Mar-20 Jul-20 Nov-20 Mar-21 Jul-21 Nov-18 Mar-19 Jul-19 Nov-19 Mar-20 Jul-20 Nov-20 Mar-21 Jul-21

Redlands Hall, Ickleton - CAM CHALK Linton - CAM CHALK Ranking derived from data for the period Aug-1963 to Dec-2017 Ranking derived from data for the period Jan-1980 to Dec-2017

30 52 29 47 28

27 42

Level (mAOD) Level 26 Level (mAOD) Level 37 25

24 32 Nov-18 Mar-19 Jul-19 Nov-19 Mar-20 Jul-20 Nov-20 Mar-21 Jul-21 Nov-18 Mar-19 Jul-19 Nov-19 Mar-20 Jul-20 Nov-20 Mar-21 Jul-21

Gog Magog, Stapleford - CAM CHALK Bury St Edmunds - UPPER LARK CHALK Ranking derived from data for the period Jan-1980 to Dec-2017 Ranking derived from data for the period May-1983 to Dec-2017

18 33 32 17 31

16 30

15 29 28

14 Level (mAOD) Level Level (mAOD) Level 27

13 26

25 12 Nov-18 Mar-19 Jul-19 Nov-19 Mar-20 Jul-20 Nov-20 Mar-21 Jul-21 Nov-18 Mar-19 Jul-19 Nov-19 Mar-20 Jul-20 Nov-20 Mar-21 Jul-21

Newmarket - SNAIL CHALK Kenninghall - LITTLE OUSE CHALK Ranking derived from data for the period Feb-1983 to Dec-2017 Ranking derived from data for the period Aug-1973 to Dec-2017

17.0 33 16.5 32 16.0 31 15.5 30 15.0 29 14.5 28 14.0 27

Level (mAOD) Level 26

Level (mAOD) Level 13.5 13.0 25 24 12.5 23 12.0 Nov-18 Mar-19 Jul-19 Nov-19 Mar-20 Jul-20 Nov-20 Mar-21 Jul-21 Nov-18 Mar-19 Jul-19 Nov-19 Mar-20 Jul-20 Nov-20 Mar-21 Jul-21

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Exceptionally high Notably high Above normal Normal - - - - Max Below normal Notably low Exceptionally low ─── Latest data - - - - Min Breckland - WISSEY CHALK Washpit Farm, Rougham - NW NORFOLK CHALK Ranking derived from data for the period Jan-1971 to Nov-2017 Ranking derived from data for the period May-1950 to Dec-2017

31 50 30

29 48 28 46 27

26 44 Level (mAOD) Level Level (mAOD) Level 25 42 24 40 23 Nov-18 Mar-19 Jul-19 Nov-19 Mar-20 Jul-20 Nov-20 Mar-21 Jul-21 Nov-18 Mar-19 Jul-19 Nov-19 Mar-20 Jul-20 Nov-20 Mar-21 Jul-21

Bircham Newton - NW NORFOLK CHALK Castle Farm, Offton - MID SUFFOLK CHALK Ranking derived from data for the period Mar-1995 to Sep-2017 Ranking derived from data for the period Mar-1967 to Dec-2017

46 24.0

22.0 44 20.0 42 18.0 40

16.0

Level (mAOD) Level Level (mAOD) Level

38 14.0

12.0 36 Nov-18 Mar-19 Jul-19 Nov-19 Mar-20 Jul-20 Nov-20 Mar-21 Jul-21 Nov-18 Mar-19 Jul-19 Nov-19 Mar-20 Jul-20 Nov-20 Mar-21 Jul-21

Old Primary School, South Creake Hazlewood Common - SUFFOLK CRAG NW NORFOLK CHALK Ranking derived from data for the period Oct-1988 to Feb-2020 Ranking derived from data for the period Oct-1971 to Dec-2017 24 3.0 2.8 23 2.6 22 2.4 2.2 21 2.0 20 1.8

Level (mAOD) Level 1.6 Level (mAOD) Level 19 1.4 18 1.2 1.0 17 Nov-18 Mar-19 Jul-19 Nov-19 Mar-20 Jul-20 Nov-20 Mar-21 Jul-21 Nov-18 Mar-19 Jul-19 Nov-19 Mar-20 Jul-20 Nov-20 Mar-21 Jul-21

The Spinney, Costessey - WENSUM CHALK Smeetham Hall Cottages, Bulmer - ESSEX CHALK Ranking derived from data for the period Oct-1971 to Dec-2017 Ranking derived from data for the period Jan-1964 to Dec-2017

12.0 30.0

11.5 29.0 11.0 28.0 10.5

10.0 27.0

9.5 26.0 Level (mAOD) Level Level (mAOD) Level 9.0 25.0 8.5 24.0 8.0 Nov-18 Mar-19 Jul-19 Nov-19 Mar-20 Jul-20 Nov-20 Mar-21 Jul-21 Nov-18 Mar-19 Jul-19 Nov-19 Mar-20 Jul-20 Nov-20 Mar-21 Jul-21

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Exceptionally high Notably high Above normal Normal - - - - Max Below normal Notably low Exceptionally low ─── Latest data - - - - Min Hindolveston - NORFOLK CHALK Rook Hall, Braiseworth - SUFFOLK CHALK Ranking derived from data for the period Sep-1984 to Nov-2017 Ranking derived from data for the period Jan-1980 to Dec-2017

57.0 34.0 56.7 33.5 56.4 33.0 56.1 32.5 55.8 55.5 32.0

55.2 31.5 Level (mAOD) Level Level (mAOD) Level 54.9 31.0 54.6 30.5 54.3 30.0 54.0 Nov-18 Mar-19 Jul-19 Nov-19 Mar-20 Jul-20 Nov-20 Mar-21 Jul-21 Nov-18 Mar-19 Jul-19 Nov-19 Mar-20 Jul-20 Nov-20 Mar-21 Jul-21

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Reservoir Stocks August 2021

─── 2020-2021 ─── Normal Operating Curve ─── Drought Alert Curve ── ─ 1995-1996

Grafham Alton

100 100 90 90 80 80 70 70 60 60 50 50 40 40 30 30

20 20

Percentage of live capacity live of Percentage capacity live of Percentage 10 10 0 0 Jan Mar May Jul Sep Nov Jan Mar May Jul Sep Nov Jan Mar May Jul Sep Nov Jan Mar May Jul Sep Nov

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─── 2020-2021 ─── Normal Operating Curve ─── Drought Alert Curve ── ─ 1995-1996

Ardleigh Abberton

100 100 90

80 80 70

60 60 50 40 40 30

20 20 n.b. from 20/01/2014 Abberton %full is based

Control curve 1 Percentage of live capacity live of Percentage Percentage of live capacity live of Percentage on increased “19m.Volume” Control curve 2 n.b. from 29/09/2014 Abberton %full is based 10 on increased “20m.Volume” 0 0 Jan Mar May Jul Sep Nov Jan Mar May Jul Sep Nov Jan Mar May Jul Sep Nov Jan Mar May Jul Sep Nov

Hanningfield

100 90 80 70 60 50 40 30 20

Control curve Percentage of live capacity live of Percentage 10 0 Jan Mar May Jul Sep Nov Jan Mar May Jul Sep Nov

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Forward Look – River Flows

Exceptionally high or low levels are those which would typically occur 5% of the time within the historic record. Notably high or low levels are those which would typically occur 8% of the time. Above normal or below normal levels are those which would typically occur 15% of the time. Normal levels are those which would typically occur 44% of the time within the historic record.

Probabilistic ensemble projections of river flows at key indicator sites in September 2021. Pie charts indicate probability, based on climatology, of the surface water flow at each site being e.g. exceptionally low for the time of year. (Source: Centre for Ecology and Hydrology, Environment Agency) Geological map reproduced with kind permission from UK Groundwater Forum, BGS © NERC. Crown copyright. All rights reserved. Environment Agency, 100026380, 2021. ^ “Naturalised” flows are projected for these sites’

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Probabilistic ensemble projections of river flows at key indicator sites in December 2021. Pie charts indicate probability, based on climatology, of the surface water flow at each site being e.g. exceptionally low for the time of year. (Source: Centre for Ecology and Hydrology, Environment Agency) Geological map reproduced with kind permission from UK Groundwater Forum, BGS © NERC. Crown copyright. All rights reserved. Environment Agency, 100026380, 2021

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Forward Look - Groundwater

Probabilistic ensemble projections of groundwater levels at key indicator sites for end of September 2021. Pie charts indicate probability, based on climatology, of the groundwater level at each site being e.g. exceptionally low for the time of year. (Source: Environment Agency) Geological map reproduced with kind permission from UK Groundwater Forum, BGS © NERC. Crown copyright. All rights reserved. Environment Agency, 100026380, 2021.

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Probabilistic ensemble projections of groundwater levels at key indicator sites for end of March 2022. Pie charts indicate probability, based on climatology, of the groundwater level at each site being e.g. exceptionally low for the time of year. (Source: Environment Agency) Geological map reproduced with kind permission from UK Groundwater Forum, BGS © NERC. Crown copyright. All rights reserved. Environment Agency, 100026380, 2021.

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Glossary Term Definition

Aquifer A geological formation able to store and transmit water.

Areal average rainfall The estimated average depth of rainfall over a defined area. Expressed in depth of water (mm).

Artesian The condition where the groundwater level is above ground surface but is prevented from rising to this level by an overlying continuous low permeability layer, such as clay.

Artesian borehole Borehole where the level of groundwater is above the top of the borehole and groundwater flows out of the borehole when unsealed.

Cumecs Cubic metres per second (m3s-1)

Effective rainfall The rainfall available to percolate into the soil or produce river flow. Expressed in depth of water (mm).

Flood Alert/Flood Warning Three levels of warnings may be issued by the Environment Agency. Flood Alerts indicate flooding is possible. Flood Warnings indicate flooding is expected. Severe Flood Warnings indicate severe flooding.

Groundwater The water found in an aquifer.

Groundwater level The water level measured in the aquifer at a borehole, which may include the impacts of artificial influences. Long term average (LTA) The arithmetic mean calculated from the historic record, usually based on the period 1961-1990. However, the period used may vary by parameter being reported on (see figure captions for details).

mAOD Metres Above Ordnance Datum (mean sea level at Newlyn Cornwall).

MORECS Met Office Rainfall and Evaporation Calculation System. Met Office service providing real time calculation of evapotranspiration, soil moisture deficit and effective rainfall on a 40 x 40 km grid.

Naturalised flow River flow with the impacts of artificial influences removed. Artificial influences may include abstractions, discharges, transfers, augmentation and impoundments.

NCIC National Climate Information Centre. NCIC area monthly rainfall totals are derived using the Met Office 5 km gridded dataset, which uses rain gauge observations.

Recharge The process of increasing the water stored in the saturated zone of an aquifer. Expressed in depth of water (mm).

Reservoir gross capacity The total capacity of a reservoir.

Reservoir live capacity The capacity of the reservoir that is normally usable for storage to meet established reservoir operating requirements. This excludes any capacity not available for use (e.g. storage held back for emergency services, operating agreements or physical restrictions). May also be referred to as ‘net’ or ‘deployable’ capacity.

River Flow The flow in the river measured at a gauging station which includes the upstream impact of artificial influences. Soil moisture deficit (SMD) The difference between the amount of water actually in the soil and the amount of water the soil can hold. Expressed in depth of water (mm).

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